BACKGROUND OF THE INVENTION
1. Field of the Invention:
[0001] This invention relates generally to sheet accumulators and more particularly to an
improved accumulator mechanism and an improved method for the accumulation into stacks
of a number of seriatim-fed sheets, including different sizes, selectively in the
manner of "over" or "under" accumulation.
2. Prior Art and Other Considerations:
[0002] Various accumulators have been employed for the accumulation into stacks of sheet
material such as paper sheets, documents, and the like. For instance, Luperti et al.
disclose in U.S. Patent No. 4,805,891 a standard and reverse collator for stacking
sheets of paper fed in seriatim thereto from a singulating feeder in the same or reverse
order as the sheets appear in the singulating feeder. Sheets are fed between moving,
endless, elastic belts; ride over a stationary ramp guide; and, are thusly delivered
over or under prior sheets that have been stopped against a registration device. Adjustment
of the location of the ramp guide provides for delivery over or under prior sheets.
The registration device is movable to release an accumulated stack of sheets for further
transport after a desired number of sheets has been accumulated. Another example of
an accumulator that relies on a similar ramp-guide mechanism is disclosed by Golicz
in U.S. Patents Nos. 4,799,663; 4,925,362; and 4,925,180.
[0003] Whereas prior art accumulators are in many ways satisfactory, high-speed handling
imposes rather strict requirements upon reliability of operation and accuracy of registration
of sheets in an accumulated stack. Moreover, interposition of stationary members,
such as ramps, in the delivery path of sheets causes possibly undesirable, inadequately-controllable
frictional effects between ramp surfaces and sheets that can result in misalignments.
Accumulating mechanisms involving significant frictional effects between stationary
members and the sheets have not been entirely satisfactory in high-volume and high-speed
sheet processing particularly for accumulating different and mixed sheet sizes and
sheets that are relatively short in the direction of transport. Further, the need
for sheet handling equipment to reliably accumulate sheets into larger stacks imposes
additional stringency on reliability and accuracy of operation. Hence, inadequately-controllable,
varying frictional effects have been found to be undesirable.
[0004] The roller-accumulator of the present invention reduces and avoids difficulties and
problems of the aforementioned kind by positively driving sheets to the stacking location
without having to encounter stationary members along which undesirable frictional
effects might arise.
[0005] Accordingly, an important overall feature of the invention is the provision of an
improved accumulator and an improved method for the accumulation into stacks of a
number of seriatim-fed sheets. The instant invention permits the selective inclusion
of different sheet sizes, in the manner of "over" or "under" accumulation, wherein
the accumulator mechanism drives sheets between moving belts so that they are positively
nipped between moving rollers to a stacking location.
SUMMARY
[0006] In accordance with principles of the present invention, a roller-accumulator is provided
for the accumulation into stacks of a number of seriatim-fed sheets, including different
sizes, selectively in the manner of "over" or "under" accumulation, wherein the roller-accumulator
mechanism drives sheets between moving belts which are positively nipped between moving
rollers to a stacking location. The sheets (in the stack) are stopped in the stacking
location against a selectively-releasable stop gate. The stack is driven to further
stack handling equipment upon release of the stack by the stop gate.
[0007] The roller-accumulator comprises an upper and a lower set of driven, endless, elastic
belts to drive sheets therebetween. Selectively positionable roller means including
driven rollers have a nip therebetween for capturing sheets driven into the nip by
the elastic belts. The sheets are positively fed between the elastic belts to a stacking
location to be accumulated over or under a previously arrived sheet. The roller nip
is offset in relation to the plane in which the sheets are driven thereto by the belts.
Further included in the roller-accumulator is a stop gate means for stopping sheets
fed to the stacking location and for selectively releasing accumulated stacks to be
transported to further equipment by and between the endless elastic belts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing and other objects, features and advantages of the invention will be
apparent from the following more particular description of preferred embodiments of
the invention, as illustrated in the accompanying drawings. The drawings are schematic
and not necessarily to scale, emphasis instead being placed upon illustrating principles
of the invention:
FIG. 1 is a schematic side elevational view of a roller-accumulator according to the
invention;
FIGS. 2 and 3 are enlarged schematic fragmentary side views of a portion of the roller
means also shown in FIG. 1; and,
FIG. 4 is a schematic fragmentary top view of a portion of the roller-accumulator
shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] Referring now to the drawings of FIGS. 1-3, there is shown an embodiment of the roller-accumulator
of the present invention comprising upper endless elastic belts 10 and lower endless
elastic belts 12, driven roller means 14, and stop gate means 16.
[0010] Upper belts 10 include lower reaches 18 and lower belts 12 include upper reaches
20. Belts 10 and 12 are driven so that reaches 18 and 20 move at substantially the
same speed in a common direction from left to right; as also indicated by the direction
of arrows 21 and 22. Reaches 18 and 20 are substantially disposed in and thereby define
a generally horizontal common plane 24. A stacking region 26 is disposed between and
along reaches 18 and 20 substantially in and parallel to common plane 24.
[0011] Driven roller means 14 is disposed upstream from stacking region 26 and comprises
upper rollers 28 and lower rollers 30, two mounting blocks 32, and vertical adjustment
and presetting means 34. Lower rollers 30 are mounted on a shaft 36 having a fixed
axis in relation to block 32 and are driven (clockwise) via a pulley 38 from drive
means not shown here. Upper rollers 28 are driven by the lower rollers 30 (counterclockwise).
The upper rollers 28 are spring-loaded against the lower rollers 30 by spring-loading
arrangement 42. Nip 40 is shown upwardly offset from the common plane 24 in FIGS.
1 and 2 and this upward offset is designated in FIG. 2 by the letters 'UO'. In FIG.
3, nip 40 is shown downwardly offset from the common plane 24, and this downward offset
is designated by the letters 'DO'. The alternate downward offset is also indicated
in FIG. 1 by dotted outlines of the rollers (28 and 30). Rollers 28 and 30 have peripheral
surfaces that are made of a high-friction elastomer material. For instance, a preferred
material has been found to be polyurethane having a hardness of durometer 83 Shore
A. It will be seen from the drawings that rollers 28 and 30 revolve about axes that
are disposed in a common axis plane which is oriented substantially perpendicularly
to common plane 24.
[0012] Shaft 36 (of lower rollers 30) is borne in mounting block 32. Upper rollers 28 are
idlers and can be individually spring-loaded or they can be borne on a common shaft
that is spring-loaded downwardly. In either case, both sets of rollers are supported
in block 32. As will be described in more detail in conjunction with FIG. 4, two mounting
blocks are provided, one each located laterally from the endless elastic belts 10
and 12, to appropriately support the sets of rollers 28 and 30 in the driven roller
means 14.
[0013] Generally vertical adjustment and setting of offset 'UO' or 'DO' is provided by adjustment
means 34 which includes two commonly driveable lead-screws 44 that are borne in support
arrangements 46. A connecting shaft 48 connects the generally vertically-oriented
lead-screws 44 between the lower support arrangements 46 (one each being disposed
laterally with respect to elastic belts 10 and 12). Adjustment means 34 further includes
motor means 50 for powered adjustment and setting of offset ('UO' and 'DO'). Motor
means 50 is arranged to drive lead-screws 44 via connecting shaft 48. Mounting blocks
32 are borne movably along the lead-screws 44 and are thereby commonly vertically
setable and adjustable. Support arrangements 46 are fixedly mounted in a machine frame
52.
[0014] Stop gate means 16 comprises an axle 56, interposer members 58 mounted on axle 56,
support block arrangements 60 in which axle 56 is borne, and electric motor means
62. Motor 62 is selectively actuateable for rotating axle 56 and therewith interposer
members 58 between two approximately orthogonal orientations as indicated in FIG.
1. Interposer members 58 are oriented substantially perpendicularly with respect to
common plane 24 in one of the orientations so that they are interposed in the path
of sheets between reaches 18 and 20 to stop the sheets from traveling further. The
interposer members 58 are rotated out of this path in the other orientation, whereby
any accumulated sheets (a stack, for instance) are released and freed to be further
transported between reaches 18 and 20.
[0015] Electric motor means 62 is preferably a rotary solenoid. Stop gate means 16 further
comprises means for adjusting the distance of interposer members 58 from driven roller
means 14 (along common plane 24). This means for adjusting includes two commonly-driveable
lead-screws 64 along which support block arrangements 60 are movable. This adjustment
is provided to accommodate the handling of different sheet lengths. For instance,
sheet lengths (in the direction of motion) of as short as 2 inches can be accommodated
in this way. Lead-screws 64 are borne in support blocks 66 that are affixed to the
machine frame 52. Lead-screws 64 are laterally disposed on either side of belts 10
and 12 and are connected by a connecting drive shaft 68 to provide for common rotation
of the lead-screws. Electric motor means 70 is provided to drive the lead-screws and
thereby to adjust the position of stop gate means along the direction of motion of
reaches 18 and 20.
[0016] A stack 74 of accumulated sheets is shown in FIG. 1 in stacking region 26. Although
belts 10 and 12 are driven continuously with reaches 18 and 20 moving from left to
right, the sheets in stack 74 are stopped with their leading edges in registration
against interposer member 58.
[0017] FIG. 2 depicts an enlarged schematic side view of salient components of driven roller
means 14 in relation to upper and lower reaches 18 and 20 of belts 10 and 12, respectively,
as seen from a similar point of view as shown in FIG. 1. The stack 74 is depicted
here by its trailing portion only. It should be understood that stack 74 is disposed
between lower and upper reaches 18 and 20, the reaches being disposed in different
interlaced transverse locations and being vertically slightly interlaced, as customary
in sheet conveying between belts. Consequently, stack 74 and any conveyed sheets are
transversely slightly corrugated in wave-like manner; hence the stack does not appear
to be located between the reaches 12 and 20 in the depicted view.
[0018] FIG. 2 shows nip 40 offset upwardly by upward offset 'UO' with respect to common
plane 24 (as also shown in FIG. 1). Further shown by dash-dot lines is an upper path
76 that is followed by a seriatim-fed sheet through nip 40 and on top of stack 74.
In other words, when nip 40 is offset to upward offset 'UO', sheets are positively
fed through the nip to stacking region 26 in the manner of an "over" accumulation.
It will be understood that a thusly fed sheet is pulled up (and thereby corrugated)
out of the plane 24 at the transverse locations of nips 40 by the nips, yet a sheet
will pass in contact with and beneath lower reach 18 and above upper reach 20 at transverse
locations corresponding to the respective reaches.
[0019] As a consequence of the pulling-up of transverse portions of the sheet at nips 40,
lower reaches 18 are pulled up too, but to a much lesser degree. This effect is utilized
to stack a nip-fed sheet on top of the previously arrived and stopped sheet in stacking
region 26, since it provides for a slight gap at least in the region of the lower
reach 18 and the trailing edge of the last (topmost) accumulated sheet.
[0020] FIG. 3, depicts a similar view as given by FIG. 2, except that the indicated partial
stack is designated by numeral 78 and that nip 40 is shown here offset downwardly
by downward offset 'DO' with respect to common plane 24. The remarks given in conjunction
with FIG. 2 in respect to the disposition of stack 74 between lower and upper reaches
18 and 20 and the transverse and vertical interlacing of reaches 18 and 20 apply similarly
to FIG. 3 and stack 78 shown therein. Further, stack 78 and any conveyed sheets are
similarly slightly transversely corrugated in wave-like manner; hence stack 78 does
not appear to be located between the reaches 12 and 20 in the depicted view of FIG.
3.
[0021] FIG. 3 shows nip 40 offset downwardly by downward offset 'DO' with respect to common
plane 24. Further shown by dash-dot lines is a lower path 80 that is followed by a
seriatim-fed sheet through nip 40 and beneath stack 78. In other words, when nip 40
is offset to downward offset 'DO', sheets are positively fed through the nip to stacking
region 26 in the manner of an "under" accumulation. It will be understood that a thusly
fed sheet is pulled down (and thereby corrugated) out of the plane 24 at the transverse
locations of nips 40 by the nips, yet a sheet will pass in contact with and above
upper reach 20 and beneath lower reach 18 at transverse locations corresponding to
the respective reaches.
[0022] As a consequence of the pulling-down of transverse portions of the sheet at nips
40, upper reaches 20 are pulled down too, but to a much lesser degree. This effect
is utilized to stack a nip-fed sheet beneath the previously-arrived and stopped sheet
in stacking region 26, since it provides for a slight gap at least in the region of
the upper reach to and the trailing edge of the last (lowermost) accumulated sheet.
[0023] Depending on the setting and adjustment of the offset 'UO' or 'DO' of nip 40 with
respect to common plane 24, "over" or "under" accumulation of sheets into a stack
results. Driven roller means 14 is operative in offsetting a sheet in the direction
of the offset so that the sheet is fed to the stacking region 26 along that surface
of the immediately preceding sheet stopped therein that faces the side of the common
plane 24 on which the offset is disposed. The adjustment and setting of the offset
of nip 40 of roller means 14 with respect to common plane 24 provides for accumulation
of different numbers of sheets into stacks (of different thicknesses). For example,
as few as 2 and as many as 25 sheets or more can be stacked reliably if the offset
is appropriately adjusted.
[0024] FIG. 4, shows a top view of a fragmentary portion of the roller-accumulator of FIG.
1. Upper and lower endless elastic belts 10 and 12, respectively, are indicated in
transversely interlaced, spaced-apart dispositions. A portion of driven roller means
14 is indicated by lower rollers 30 (disposed in transverse spaces between belts 10
and 12), shaft 36, drive pulley 38 being driven by a drive belt 82 from motor means
(not shown), and one of the mounting blocks 32. Adjusting and setting means 34 for
driven roller means 14 is indicated by a portion of the support arrangement 46 and
by one of the lead-screws 44. A sheet or sheet stack 74 (or 78) is shown in stacking
region 26 stopped against interposer members 58 of stop gate means 16. Stop gate means
16 is further represented by axle 56, one of the support block arrangements 60, and
electric motor means or rotary solenoid 62. The means for adjusting the distance of
stop gate means 16 from driven roller means 14 is represented by one of the lead-screws
64. This distance is adjustable to accommodate different lengths of sheets to be accumulated.
[0025] In operation of the roller-accumulator, sheets are fed in seriatim between reaches
18 and 20 of belts 10 and 12. As the leading edge of a sheet contacts upper or lower
rollers 28 or 30 of roller means 14, the leading edge rides along the rotating periphery
of the rollers and is delivered into the nip 40 therebetween. The sheet is positively
driven through nip 40 to stacking region 26 between reaches 18 and 20. As nip 40 is
offset out of the common plane 24, the sheets passing through the nip are also offset.
Sheets are selectively stopped in the stacking region 26 against interposer member
58 of stop gate means 16 and are accumulated into a stack 74 (or 78). The stack is
selectively released by rotating interposer member 58 out of the stack path between
reaches 18 and 20, and the released stack is transported further by and between the
moving reaches.
[0026] The offset 'UO' or 'DO' of nip 40 is set selectively in accordance with the desired
stacking mode; i.e. to above common plane 24 for "over" accumulation and beneath the
common plane 24 for "under" accumulation. Also, the offset distance from common plane
24 is adjusted to accommodate stacks of different numbers of sheets and/or different
sheet material thicknesses.
[0027] It should be understood that adjustments and settings of the distance between stop
gate means 16 and roller means 14, as well as of the offset 'UO' and 'DO' can be alternately
effected manually, although the described motor-powered adjustment and setting is
preferred.
[0028] While the invention has been particularly shown and described with reference to preferred
embodiments thereof, it will be understood by those skilled in the art that various
changes and modifications in form and details may be made therein without departing
from the spirit and scope of the invention.
1. A roller-accumulator for the seriatim feeding and accumulation of sheets into stacks
and for further transportation of accumulated stacks, the roller-accumulator comprising:
upper and lower endless belt means (10,12), said upper belt (10) means having lower
reaches (18) and said lower belt means (12) having upper reaches (20), said upper
and lower reaches (18, 20) being driven in a common direction and being disposed substantially
in and thereby defining a common plane, said upper and lower reaches (18,20) being
disposed along a stacking region (26) substantially in said common plane;
driven roller means (14) for feeding therethrough sheets in seriatim delivered
thereto by said upper and lower belt means (10, 12), said driven roller means (14)
including upper and lower roller means (28, 30) having a nip (40) therebetween, said
nip (40) being disposed along said upper and lower reaches (18, 20) upstream from
said stacking region (26) and having an offset in relation to said common plane; and,
stop gate means (58) for selectively stopping and releasing sheets from said stacking
region, said stop gate means (58) being disposed along said upper and lower reaches
(18, 20) downstream from said driven roller means (14);
whereby sheets are fed in seriatim by and between said upper and lower reaches
(18, 20) into and through said nip (40) to said stacking region (26) wherein the sheets
are selectively stopped by said stop gate means (58) and stacked into stacks that
are subsequently selectively released by said stop gate means (58) for further transport
by said upper and lower endless belt means (10, 12), said driven roller means (14)
being operative in offsetting a sheet in the direction of said offset so that the
sheet is fed to said stacking region (26).
2. The roller-accumulator according to claim 1, wherein said driven roller means includes
means for adjusting said offset to different distances from said common plane.
3. The roller-accumulator according to claim 1, wherein said driven roller means includes
means for selection of presetting said offset to opposite sides in relation to said
common plane.
4. The roller-accumulator according to claim 1, wherein said upper roller means is spring-loaded
against said lower roller means to form said nip, said lower roller means being driven
to revolve about a fixed axis.
5. The roller-accumulator according to claim 1, wherein said stop gate means comprises
an axle and an interposer member mounted on said axle, said stop gate means further
including means for rotating said axle and thereby said interposer member selectively
between first and second orientations, said interposer member being interposed into
the sheet transport path along said upper and lower reaches in said common plane while
in said first orientation, and, said interposer member being out of the way of the
sheet transport path while in said second orientation.
6. A method for the seriatim feeding and accumulation of sheets into stacks and for further
transporting accumulated stacks, comprising steps of:
feeding sheets in seriatim by and between lower reaches of upper endless belt means
and upper reaches of lower endless belt means, said upper and lower reaches being
driven in a common direction and being substantially disposed in a common plane, said
upper and lower reaches having disposed therealong driven roller means, said upper
and lower reaches having disposed therealong downstream from said driven roller means
a stacking region substantially in said common plane;
delivering the sheets to said driven roller means;
offsetting the sheets by said driven roller means out of said common plane and
nipping the sheets between upper and lower rollers of said driven roller means in
a nip having an offset with respect to said common plane;
interposing an interposer of a stop gate means into the path of sheets at the downstreamn
end of said stacking region for stopping sheets;
driving the sheets by and through said nip to said stacking region;
stopping the sheets in said stacking region against said interposer of said stop
gate means and thereby accumulating sheets into a stack; and,
selectively releasing the stack by moving said interposer out of the way of the
path of sheets and transporting the stack further between said upper and lower reaches.
7. The method according to claim 6, further comprising a step of adjusting said offset
to different distances from said common plane.
8. The method according to claim 6, further comprising the step of selectively presetting
said offset to opposite sides in relation to said common plane.
9. The method according to claim 6, further comprising the step of adjusting the distance
between said stop gate means and said driven roller means for the accommodation of
different lengths of sheets.
10. The method of claim 9, wherein said step of adjusting the distance includes driving
said stop gate means to different distances from said driven roller means, said driving
being effected by electric motor means.